Photographer Martin Bennett of Swindon,
Wiltshire, England, took this fantastic photo of mom, dad, and the three
kids (how does he get the baby to sit still like that?): Link
- via Neatorama's Facebook
Page

It's just a guess, but I'd say the photos were taken individually and the negatives somehow overlapped in the printing process, so that the chins and eyes line up. There's some 'wiggle room' in the deep shadows on the right side of each of their faces.